Rotary recliner mechanisms typically include an outer rotary member having a plurality of inwardly-projecting gear teeth and an inner rotary member having a plurality of outwardly-extending gear teeth. The gear teeth of the inner rotary member move circumferentially about the gear teeth of the outer rotary member to selectively rotate the inner rotary member relative to the outer rotary member.
The inner rotary member may include one fewer tooth than the outer rotary member and have a diameter that is smaller than the diameter of the outer rotary member. The inner rotary member is mounted on an eccentric to bias the inner rotary member in one direction relative to the outer rotary member. The eccentric mounting provides gear teeth meshing on one portion of the inner rotary member and a clearance between the remaining gear teeth of the inner rotary member and the gear teeth of the outer rotary member.
In operation, a rotational force is applied to the eccentric to rotate the inner rotary member relative to the outer rotary member. Rotation of the inner rotary member causes the area of meshed engagement to move circumferentially around the outer rotary member.
The rotary recliner mechanism may be associated with a seating system such that the inner rotary member is associated with a seat back and the outer rotary member is associated with a seat bottom. Angular adjustment of the seat back relative to the seat bottom is accomplished when a force is applied to the eccentric and the inner rotary member is rotated relative to the outer rotary member.
In a seating system for a vehicle and the like, the seat back functions as a long lever arm against which various forces are applied. Rotary recliner mechanisms are generally disposed at a junction of a seat back and a seat bottom and are relatively small compared to the length of the reclining seat back. Therefore, vibration associated with operation of a vehicle and/or movement of an occupant may impose various forces upon that lever during use.
Any imperfection in the components of pivot mechanisms associated with the rotary recliner mechanism may allow the inner rotary member connected to the seat back to move a miniscule amount even when the mechanism is locked. Such play or backlash between the engaging teeth or tolerances between the mechanism components are magnified by the length of the lever arm and become increasingly noticeable at the upper end of the seat.
This magnified play in locking pivot mechanisms has been termed “chucking” and refers to any imperfections or play in the mechanism components that allow movement of the rotary member and attached seat back while the mechanism is in a locked condition.
One technique employed to reduce chucking is to form the components of the pivot mechanism with exceedingly close tolerances. Such techniques reduce play in the mechanism, and thus reduce chucking. Manufacturing to such close tolerance, however, is expensive and difficult to achieve. Further, close tolerances may bind the components of the system and prevent smooth operation.
Another technique used to reduce chucking is to provide a rotary recliner with a wedge carrier that is biased into engagement with the eccentric. A prior art rotary recliner 1 and wedge carrier 2 is shown in FIGS. 1 and 2 as having two discrete wedges 3 that each include a ramped surface 4 for engagement with an eccentric 5. The discrete wedges 3 are spaced apart and apply a radial force on the eccentric 5 under force of a biasing member 6.
In operation, once an adjustment is made, such that an inner rotary member 7 is in a desired position relative to an outer rotary member 8, a rotational force applied to the eccentric 5 is released. Upon release of the rotational force, each ramped surface 4 of the discrete wedges 3 is biased into engagement with the eccentric 5. The wedges 3 individually apply a force to the eccentric 5 to maintain tight engagement between the eccentric 5 and the wedge carrier 2 as well as tight engagement between the inner rotary member 7 and the outer rotary member 8 at the area of meshed engagement. Maintaining engagement between the eccentric 5 and the carrier 2 as well as between the inner rotary member 7 and the outer rotary member 8 reduces relative movement between the respective components and, thus, reduces chucking. An example of such a wedge carrier having discrete wedges is shown in U.S. Pat. No. 5,524,970.
Prior art wedge carriers and discrete wedges adequately reduce movement between the inner rotary member and outer rotary member. However, the prior art system is complex and often expensive to manufacture. The discrete wedges extend from a main body of the carrier and are therefore delicate and subject to fracture. As a result, the carrier of the prior art system cannot be manufactured by a process requiring a heat treatment. Therefore, the carrier of the prior art system requires a precision manufacturing process, resulting in high manufacturing and assembly costs.